1. Field of the Invention
The present invention relates to a laminated heat exchanger used, for instance, as a heater core, or an evaporator in an air conditioning system for vehicles.
2. Description of the Related Art
Well known laminated heat exchangers in the prior art include, for instance, the one shown in FIG. 1 of Japanese Unexamined Patent Publication No. S63-267868.
To outline this laminated heat exchanger, an intake piping unit 2A and an outlet piping unit 2B project out adjacent to each other approximately at the center of the front surface in the direction of air flow. The intake piping unit 2A and the outlet piping unit 2B are each formed by bonding formed plates abutted facing each other so that they are internally provided with a first space 40 and a second space 50 and a first space 61 and a second space 71 respectively.
Between the intake piping unit 2A and the outlet piping unit 2B, a central tube unit 9 is provided in such a manner that it is clamped between the two units. The central tube unit 9 is provided with a first space 48 and a second space 58.
The first space 48 of the central tube element 9 and the first space 61 of the outlet piping unit 2B are cut off from each other so that the first space 48 of the intake piping unit 2A and the first space 61 of the outlet piping unit 2B are not in communication. Furthermore, adjacent tanks communicate via holes 704, 705, 904 and 905, which are formed in the direction of the lamination.
With this, the tanks in this laminated heat exchanger are divided into an intake tank group 200, a central tank group 201 and an outlet tank group 202, to effect the flow of heat exchanging medium described below.
First, after the heat exchanging medium flows into the intake piping unit 2A to the first space 40, it travels into the intake tank group 200. The heat exchanging medium in the intake tank group 200 then travels through the first tube group 401 along its U-shaped flow path to flow into the left half of the central tank group 201.
Then, the heat exchanging medium that has flowed into the left half of the central tank group 201 flows into the right half of the central tank group 201 via the second spaces 50 and 71 of the intake piping unit 2A and the outlet piping unit 2B respectively.
The heat exchanging medium, which has thus flowed into the right half of the central tank group 201, flows through the second tube group 402 along its U-shaped flow path. Then it flows into the outlet tank group 202. After that, it flows to the left and flows out from the outlet piping unit 2B.
However, in a laminated heat exchanger provided with tank groups that effect the flow of heat exchanging medium described above, the heat exchanging medium does not flow easily in tanks that are far from the intake and outlet piping units, i.e., the tanks that are at the ends.
This causes inconsistency in the distribution of heat exchanging medium flowing in the laminated heat exchanger, which, in turn, results in poor temperature distribution of the heat exchanging medium flowing in the tube units, reducing the performance of the laminated heat exchanger.